In general, chromatography involves the flowing of a mobile phase over a stationary phase to effect separation. To speed-up and enhance the efficiency of the separation, pressurized mobile phases were introduced. For example, in carbon dioxide based chromatography systems, carbon dioxide or a carbon dioxide mixture is used as the extracting solvent in a supercritical or near supercritical fluid state. To keep the carbon dioxide in a supercritical or near supercritical fluid state the chromatography system is subjected to a predefined pressure. Most often, a back pressure regulator is employed downstream of the chromatography column to maintain the predefined pressure. Prior to entering the chromatography system a degasser or degasser unit is typically used to reduce the amount of dissolved gases in the mobile phase. After passing a mobile phase through a column to effect separation a resulting eluent may include dissolved gases due to the high system pressure. To remove a portion of the dissolved gases from the resulting eluent, the eluent typically passes through a gas-liquid separator. However, due to the system pressure required to use carbon dioxide or a carbon dioxide mixture (e.g. carbon dioxide mixed with a solvent such as methanol) in a supercritical or near supercritical fluid state, significant amounts of dissolved gas can remain in the eluent upon exiting the gas-liquid separator. High amounts of remaining dissolved gas can lead to outgassing (i.e., aerosolization) and interfere with subsequent flow and downstream processes, such as fraction collection and detection.
As such, there remains a need for robust and efficient degassing methods to minimize the outgassing of the mobile phase after separation and to enhance fraction collection yields and purity.